No matter how much you turn up the heat, you continue to shiver and chatter your teeth all winter long in your home.

While you were already considering replacing your radiators with more recent models or having a wood stove installed (all very useful initiatives!), the energy diagnosis of your home reveals that the main culprits of this heat loss are makes your attic poorly insulated.

In order to gain in comfort, reduce your bill and avoid wasting energy, insulation work is essential.

Here are five things to consider to make this project a success.

Determine the use of the attic

Before taking the slightest step, keep in mind the functionality for which you intend your attic, since this criterion will influence the choice of insulation technique and material.

Thus, the so-called "lost" or "visitable" attics are not habitable due to insufficient average free height or too bulky structural timbers.

Due to this, a thick layer of insulation will not interfere with you.

Conversely, for convertible attics, that is to say that you plan to use as living rooms, it is important to optimize the space, especially since the ceiling height is already reduced.

The insulation should therefore not be at the expense of your daily comfort and the use of this place.

For this, you will have to choose specific materials and techniques.

Choose the right insulation technique

For lost attics, we generally turn to interior insulation, most often at floor level.

To do this, one can proceed by blowing or spreading flakes of insulating products (most often wool or cellulose wadding), which is the least expensive and fastest method to carry out, or else lay rolls on the ground and between the joists.

In any case, do not forget to apply a waterproofing membrane or vapor barrier to protect the frame from humidity.

For convertible attics, opt instead for insulation outside the roof, in order to gain a few precious centimeters and not encroach on the living space.

Two techniques are therefore recommended.

That of the "sarking", which consists of laying layers of insulation between the frame and the roof, involves the complete removal of the cover.

This solution, reserved for experienced professionals, is considerably more expensive but it improves the energy performance of your home immeasurably.

Another possibility: turn to self-supporting panels, whose framework is fixed at the level of the slopes of the roof.

Choose the type of insulation

In order to insulate your spaces under the roof, you will be spoiled for choice.

Insulators of natural origin derived from plants (hemp fibres, linen felt, cellulose wadding, cotton, cork) or animals (sheep's wool, feathers) are the most environmentally friendly.

Insulators of mineral origin (glass wool, rock wool, cellular glass) are very affordable and have the advantage of being fire resistant.

Finally, synthetic insulation, such as polystyrene, phenolic foam and polyurethane, are very versatile and offer good resistance to humidity.

Whatever insulation you set your sights on, remember to check its performance, so that it complies with RT2012 thermal regulations, and allow at least 20 cm thickness for effective thermal insulation, even if certain materials innovative are very effective despite their finesse.

Last important point: if you plan windows in your attic, they must at least be equipped with double glazing.

Call a pro

Provided you are a good handyman, it is quite possible to insulate your attic yourself from the inside.

However, using a qualified craftsman is often more judicious, not only to ensure that the work is carried out according to the rules of the art and in complete safety, but also in order to receive the various financial aids for energy renovation.

OUR “HOUSING” FILE

In fact, to be eligible for MaPrimeRénov', the heating and/or insulation boost bonus, the zero-rate eco-loan and any aid granted by local authorities, you must apply for a company with the RGE label ( recognized guarantor of the environment) for your construction site.

This installer will also ensure that the insulation installed reaches the required thresholds of thermal resistance R. The additional cost generated by the use of this experienced workforce will be very largely compensated.

To find a certified professional, use the directory available on the official France-renov.gouv.fr platform.

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Focus: Think about ventilating

If the attics suffer from significant heat loss during the winter season, they can quickly become stifling in the summer, especially since the hot air tends to rise!

To avoid any thermal discomfort on hot summer days, have a ventilation system installed in your attic, preferably of the double flow VMC type.

This will allow you to ventilate this space in the evening to bring down the mercury and let in the freshness.

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